Method and apparatus for obtaining uplink timing alignment on a secondary cell

ABSTRACT

A method for uplink timing alignment in a wireless transmit/receive unit is provided. The method includes receiving control signaling from an evolved Node B, receiving on a primary cell (PCell) a physical downlink control channel (PDCCH) order, the PDCCH order including a carrier indicator field indicating a secondary cell (SCell) to transmit a physical random access channel (PRACH) transmission. In response to the PDCCH order, transmitting the PRACH transmission, and in response to the PRACH transmission, monitoring the PCELL for a random access response (RAR). In response to detecting an RAR associated with the PRACH transmission, adjusting timing for the SCell in response to a timing advance included in the RAR.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-provisional applicationSer. No. 13/468,709 filed May 10, 2012 which claims the benefit of U.S.Provisional Application No. 61/484,591 filed May 10, 2011, the contentsof which is hereby incorporated by reference herein.

BACKGROUND

Third Generation Partnership Project (3GPP) Long Term Evolution (LTE)Release 8+ operating with a single serving cell (hereafter LTE R8+)supports up to 100 Mbps in the downlink (DL), and 50 Mbps in the uplink(UL) for a 2×2 configuration. The LTE downlink transmission scheme isbased on an orthogonal frequency division multiple access (OFDMA) airinterface. For the purpose of flexible deployment, LTE R8+ systemssupport scalable transmission bandwidths, one of 1.4, 2.5, 5, 10, 15, or20 MHz.

In LTE R8+, each radio frame (10 ms) includes 10 equally sizedsub-frames of 1 ms. Each sub-frame includes 2 equally sized timeslots of0.5 ms each. There can be either seven or six orthogonal frequencydivision multiplexing (OFDM) symbols per timeslot. Seven symbols pertimeslot are used with normal cyclic prefix length, and six symbols pertimeslot can be used in an alternative system configuration with theextended cyclic prefix length. The sub-carrier spacing for the LTE R8/9system is 15 kHz. An alternative reduced sub-carrier spacing mode using7.5 kHz is also possible.

A resource element (RE) corresponds to one (1) sub-carrier during one(1) OFDM symbol interval. Twelve (12) consecutive sub-carriers during a0.5 ms timeslot constitute one (1) resource block (RB). With seven (7)symbols per timeslot, each RB includes 12×7=84 REs. A DL carrier mayconsist of scalable number of resource blocks (RBs), ranging from aminimum of six (6) RBs up to a maximum of 110 RBs. This corresponds toan overall scalable transmission bandwidth of roughly 1 MHz up to 20MHz. However, usually a set of common transmission bandwidths isspecified, for example, 1.4, 3, 5, 10 or 20 MHz.

The basic time-domain unit for dynamic scheduling is one sub-frameincluding two consecutive timeslots. This is sometimes referred to as aresource-block pair. Certain sub-carriers on some OFDM symbols areallocated to carry pilot signals in the time-frequency grid. A givennumber of sub-carriers at the edges of the transmission bandwidth arenot transmitted in order to comply with spectral mask requirements.

SUMMARY

A method for uplink timing alignment in a wireless transmit/receive unitis provided. The method includes receiving control signaling from anevolved Node B, receiving on a primary cell (PCell) a physical downlinkcontrol channel (PDCCH) order, the PDCCH order including a carrierindicator field indicating a secondary cell (S Cell) to transmit aphysical random access channel (PRACH) transmission. In response to thePDCCH order, transmitting the PRACH transmission, and in response to thePRACH transmission, monitoring the PCELL for a random access response(RAR). In response to detecting an RAR associated with the PRACHtransmission, adjusting timing for the SCell in response to a timingadvance included in the RAR.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is an example flow diagram of a network-controlled preambletransmission;

FIG. 3 shows example methods for preamble transmissions;

FIG. 4 is an example of options for handling or avoiding S Cell preamblecollisions with other uplink transmissions;

FIG. 5 shows Examples of the conditions for which the WTRU may postponeSCell preamble re(transmissions) to a subsequent occasion;

FIG. 6 shows scenarios in which a WTRU may avoid selecting a PRACH thatwould collide with another transmission;

FIG. 7 shows an example of the WTRU using a dedicated preamble and PRACHmask index to perform preamble transmission on the SCell;

FIG. 8 is an example of a network-controlled dedicated preambleretransmission;

FIG. 9 is an example of method to determine completion of thenetwork-controlled procedure;

FIG. 10 is an example E/T/RAPID MAC subheader;

FIG. 11 is an example E/T/R/R/BI MAC subheader; and

FIG. 12 is an example MAC RAR.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managementgateway entity (MME) 142, a serving gateway 144, and a packet datanetwork (PDN) gateway 146. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 142 may be connected to each of the eNode-Bs 140 a, 140 b, 140 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode-B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

In a LTE R8+ system, the network may control physical radio resourcesusing the Physical Downlink Control Channel (PDCCH). Control messagesare transmitted using specific formats, for example, downlink controlinformation (DCI) formats. A wireless transmit/receive unit (WTRU)determines whether it may act on control signaling in a given sub-frameby monitoring the PDCCH for specific data control information messages(DCI formats). The PDCCH for specific DCI formats may be scrambled usinga known radio network temporary identifier (RNTI) in specific locations,or search space, using different combinations of physical resources, forexample, control channel elements (CCEs), based on aggregation levels(AL). Each AL may correspond to either 1, 2, 4, or 8 CCEs. A CCEincludes 36 quadrature phase shift keying (QPSK) symbols, or 72 channelcoded bits.

The PDCCH is conceptually separated in two distinct regions. The set ofCCE locations in which a WTRU may find DCIs it should act on is referredto as a search space (SS). The SS is split into the common SS (CSS) andWTRU-specific SS (WTRUSS). The CSS is common to all WTRUs monitoring agiven PDCCH, while the WTRUSS differs from one WTRU to another. Both SSsmay overlap for a given WTRU in a given sub-frame as this is a functionof the randomization function, and this overlap differs from onesub-frame to another.

The set of CCE locations that makes up the CSS and its starting point isa function of the cell identity and the sub-frame number. For LTE R8/9,DCIs may only be sent with AL4 (4 CCEs) or AL8 (8 CCEs) in the CSS. Fora sub-frame for which the WTRU monitors the PDCCH, the WTRU may attemptto decode 2 DCI format sizes in up to 4 different sets of 4 CCES for AL4(or 8 blind decoding) and up to 2 different sets of 8 CCEs for AL8 (or 4blind decoding) for a total of at most 12 blind decoding attempts in theCSS. For example, the 2 DCI format sizes may be formats 1A, 1C, and 3Aused for power control.

The CSS corresponds to CCEs 0-15, implying four decoding candidates forAL4 (i.e., CCEs 0-3, 4-7, 8-11, 12-15) and two decoding candidates forAL8, for example, CCEs 0-7, 8-15.

The set of CCE locations that makes up the WTRUSS and its starting pointis a function of the WTRU identity and the sub-frame number. For LTER8+, DCI may be sent with AL1, AL2, AL4 or AL8 in the WTRUSS. For asub-frame for which the WTRU monitors the PDCCH, the WTRU may attempt todecode 2 DCI formats in up to 6 different CCES for AL1 (i.e., 12 blinddecoding), up to 6 different sets of 2 CCEs for AL2 (i.e., 12 blinddecoding), up to 2 different sets of 4 CCEs for AL4, for example, 4blind decoding, and up to 2 different sets of 8 CCEs for AL8, forexample, 4 blind decoding, for a total of at most 32 blind decodingattempts in the WTRUSS.

The DCI formats which the WTRU decodes depends on the configuredtransmission mode, for example, whether or not spatial multiplexing isused. There are a number of different DCI formats; for example, format 0(UL grant), format 1 (non-MIMO), format 2 (DL MIMO) and format 3 (powercontrol). The version of each DCI format(s) the WTRU decodes is governedat least in part by the configured transmission mode, for example, modes1-7.

A summary list with typical usage is presented below:

-   -   DCI format 0 (UL grant)    -   DCI format 1 (DL assignment)    -   DCI format 1A (compact DL assignment/PDCCH order for random        access)    -   DCI format 1B (DL assignment with precoding info)    -   DCI format 1C (very compact DL assignment)    -   DCI format 1D (compact DL assignment with precoding info+power        offset info)    -   DCI format 2 (DL assignment for spatial multiplexing)    -   DCI format 2A    -   DCI format 3 (TPC for PUCCH/PDSCH, two bits)    -   DCI format 3A (TPC for PUCCH/PDSCH, single bit)

A table illustrating the different DCI sizes resulting from differentsystem bandwidth configurations is provided in Table 1.

TABLE 1 Bandwidth 6 15 25 50 75 100 Format 0 37 38 41 43 43 44 Format 1A37 38 41 43 43 44 Format 3/3A 37 38 41 43 43 44 Format 1C 24 26 28 29 3031 Format 1 35 39 43 47 49 55 Format 1B (2 tx ant) 38 41 43 44 45 46Format 1D (2 tx ant) 38 41 43 44 45 46 Format 2 (2 tx ant) 47 50 55 5961 67 Format 2A (2 tx ant) 44 47 52 57 58 64 Format 1B (4 tx ant) 41 4344 46 47 49 Format 1D (4 tx ant) 41 43 44 46 47 49 Format 2 (4 tx ant)50 53 58 62 64 70 Format 2A (4 tx ant) 46 49 54 58 61 66

In LTE R8+ systems, whether the control signaling received on a PDCCHpertains to the uplink component carrier or to the downlink componentcarrier is related to the format of the DCI decoded by the WTRU, and theDCI formats are used to control the WTRUs communication on the uplinkcomponent carrier and on the DL component carrier of the cell on towhich the WTRU is connected.

A WTRU may request radio resources for an uplink transmission by sendinga scheduling request (SR) to the eNB. The SR may be transmitted eitheron dedicated resources (D-SR) on the Physical Uplink Control Channel(PUCCH) if configured, or using the Random Access procedure (RA-SR).

For an LTE serving cell, a WTRU may determine uplink radio link failurewhen it reaches the maximum number of preamble transmissions for therandom access procedure and/or repeated failure to perform the randomaccess procedure on the concerned serving cell.

For an LTE serving cell, a WTRU may determine DL radio link failure whenthe radio resource control (RRC) instance receives a predeterminednumber (N310) of consecutive “out-of-synch” indications from thephysical layer and a timer T310 subsequently expires while the WTRU hasnot recovered from the error condition that started the timer.

LTE-Advanced operating with multiple serving cells (LTE R10+) is anevolution that aims to improve LTE R8+ data rates using, among othermethods, bandwidth extensions, also referred to as carrier aggregation(CA). With CA, a WTRU may transmit and receive simultaneously over thephysical uplink shared channel (PUSCH) and the physical downlink sharedchannel (PDSCH), respectively, of multiple serving cells. Up to fiveserving cells (possibly with or without configured uplink resources) maybe used thus supporting flexible bandwidth assignments up to 100 MHz. Inaddition to the baseline functionality of LTE R8+, a number ofadditional methods have been introduced to support the simultaneousoperation of a WTRU on multiple serving cells.

The control information for the scheduling of PDSCH and PUSCH may besent on one or more PDCCH(s). In addition to the LTE R8+ schedulingusing one PDCCH for a pair of UL and DL carriers, cross-carrierscheduling may also be supported on the PDCCH of a serving cell, forexample, the primary cell (PCell), allowing the network to provide PDSCHassignments and/or PUSCH grants for any other serving cell, for example,a secondary cell (S Cell). When cross-carrier scheduling is used, a3-bit carrier indicator field (CIF) may be used to address the concernedS Cell, where each S Cells identifier is derived from RRC configuration.

When referred to hereafter, the term “component carrier (CC)” includes,without loss of generality, a frequency on which the WTRU operates. Forexample, a WTRU may receive transmissions on a downlink CC (DL CC). A DLCC may comprise a plurality of DL physical channels. A WTRU may performtransmissions on an uplink CC (UL CC). A UL CC may comprise a pluralityof UL physical channels.

For example, for LTE the downlink physical channels may include, whilenot being limited to, a Physical Control Format Indicator Channel(PCFICH), a Physical Hybrid ARQ Indicator Channel (PHICH), a PhysicalDownlink Control Channel (PDCCH), a Physical Multicast data Channel(PMCH) and a Physical Downlink Shared Channel (PDSCH). On the PCFICH,the WTRU may receive control data indicating the size of the controlregion of the DL CC. On the PHICH, the WTRU may receive control dataindicating hybrid automatic repeat request (HARQ) positiveacknowledgement/negative acknowledgement feedback (HARQ A/N, HARQACK/NACK or HARQ-ACK) for a previous uplink transmission. On the PDCCH,the WTRU may receive downlink control information (DCI) messages, mainlyused for the purpose of scheduling of downlink and uplink resources. Onthe PDSCH, the WTRU may receive user and/or control data. For example, aWTRU may transmit on an uplink CC (UL CC).

For example, for LTE the uplink physical channels may include, while notbeing limited to, a Physical Uplink Control Channel (PUCCH) and aPhysical Uplink Shared Channel (PUSCH). On the PUSCH, the WTRU maytransmit user and/or control data. On the PUCCH, and in some case on thePUSCH, the WTRU may transmit uplink control information (UCI). UCI mayinclude a channel quality indicator (CQI), precoding matrix indicator(PMI), rank indicator (RI), or scheduling request (SR), or HARQ ACK/NACKfeedback. On a UL CC, the WTRU may also be allocated dedicated resourcesfor transmission of sounding reference signals (SRS).

A cell may comprise a DL CC which may be linked to a UL CC based on thesystem information (SI) received by the WTRU. The SI may be broadcastedon the DL CC or using dedicated configuration signaling from thenetwork. For example, when broadcasted on the DL CC, the WTRU mayreceive the uplink frequency and bandwidth of the linked UL CC as partof a system information element. For example, the WTRU may receive theuplink frequency and bandwidth of the linked UL CC as part of the systeminformation element when in RRC_IDLE for LTE, when in IDLE or CELL_FACHfor WCDMA, or when the WTRU does not yet have a radio resourceconnection to the network.

When referred to hereafter, the term “PCell” includes, without loss ofgenerality, the cell operating of the primary frequency in which theWTRU may perform the initial access to the system or the cell indicatedas the primary cell in the handover procedure, or the like. For example,the initial connection access to the system may be the initialconnection establishment procedure or the connection re-establishmentprocedure. PCell may correspond to a frequency indicated as part of theradio resource connection configuration procedure. Some functions may ormay not be supported on the PCell. For example, the UL CC of the PCellmay correspond to the CC whose physical uplink control channel resourcesare configured to carry all HARQ ACK/NACK feedback for a given WTRU.

For example, in LTE the WTRU may use the PCell to derive the parametersfor the security functions and for upper layer system information suchas non-access stratum (NAS) mobility information. Other functions thatmay be supported on the PCell DL include system information (SI)acquisition and change monitoring procedures on the broadcast channel(BCCH), and paging.

When referred to hereafter, the term “SCell” includes, without loss ofgenerality, the cell operating on a secondary frequency which may beconfigured once a radio resource control connection is established andwhich may be used to provide additional radio resources. Systeminformation relevant for operation in the concerned SCell may beprovided using dedicated signaling when the SCell is added to the WTRU'sconfiguration. Although the parameters may have different values thanthose broadcasted on the downlink of the concerned SCell using the SIsignaling, this information may be referred to as SI of the concerned SCell independently of the method used by the WTRU to acquire thisinformation.

When referred to hereafter, the terms “PCell DL” and “PCell UL”corresponds to, without loss of generality, the DL CC and the UL CC ofthe PCell, respectively. Similarly, the terms “S Cell DL” and “SCell UL”corresponds to the DL CC and the UL CC (if configured) of an SCell,respectively.

When referred to hereafter, the term “serving cell” includes, withoutloss of generality, a PCell or an SCell. More specifically, for a WTRUthat is not configured with any SCell or that does not support operationon multiple CCs, for example, carrier aggregation, there may be oneserving cell comprising of the PCell. For a WTRU that is configured withat least one SCell, the term “serving cell” includes one or more cellscomprising the PCell and all configured SCell(s).

When a WTRU is configured with at least one SCell, there may be onePCell DL and one PCell UL and, for each configured SCell, there may beone S Cell DL and one SCell UL (if configured).

When referred to hereafter, the term “timing advance (TA) Group” (TAG)includes, without loss of generality, one or more serving cells forwhich a WTRU may apply the same timing advance offset. For example oneor more serving cells may be configured with uplink resources. Forexample, the same timing advance offset may be using a downlink timingreference for each cell, which reference may or may not be the same cellfor all cells of a group. The cells configured for a WTRU may beassociated to either the primary TAG or to a secondary TAG. For example,a single time advance command (TAC), either received in a random accessresponse (RAR) or in a MAC control element (CE), may apply to the TAcorresponding to the uplink transmission of any serving cell in the sameTAG.

For each cells with configured uplink within a TA group, the WTRU mayapply the same TA offset. Assuming that an WTRU supports at most twoTAs, the configured cells may be associated to either the primary TAgroup or to the secondary TA group. The PCell may be part of the primaryTA group.

A primary TAG may include at least the PCell and zero or more SCells forwhich SCells, if configured with resources for uplink transmissions, mayshare the same uplink synchronization characteristics. For example, theSCells may use the PCell DL as the timing reference for uplinktransmissions.

A secondary TAG may include one or more SCells for which SCells, ifconfigured with resources for uplink transmissions, may share the sameuplink synchronization characteristics. For example, a secondary TAG mayuse either the S Cell DL of one of the S Cells of the same TAG or theirassociate S Cell DL and may apply the same TA. Whether or not an SCellconfigured with uplink resources belongs to the primary TAG or to asecondary TAG, the SCell may be configured semi-statically, for exampleusing RRC control signaling. For example, when an SCell is added ormodified in the WTRU configuration.

Examples disclosed herein are related to how a mobile wireless terminal,for example, a WTRU, when configured for multicarrier operation, maygain uplink timing alignment on an S Cell of its multicarrierconfiguration.

For the random access procedure on the PCell in LTE R8+, the WTRU maymonitor the PDCCH for random access RNTI (RA-RNTI) in the PDCCH CSSduring the RAR window.

In LTE R11, the WTRU may support a random access procedure, or a similarmethod to obtain uplink timing alignment, in particular for gaininguplink timing advance. If a RACH procedure may be performed on SCells, aWTRU may monitor the PDCCH for decoding of RA-RNTI for reception of anRAR. For SCells, in R10 there may be no DCI that needs to be decoded inthe CSS for SCells. Thus, SCells may not define a CSS on the PDCCH oftheir corresponding SCell DL for R10 WTRUs. Introducing an RACH onSCells may require that the WTRU monitors the RA-RNTI for SCells for theRAR. SCells in LTE R10 define a WTRU search space (WTRUSS) on the PDCCH,and no CSS. Thus, it may not be possible to receive a DCI scrambled withan RA-RNTI on the PDCCH of an SCell.

Examples where a WTRU may monitor the CSS of an SCell, for the RACHprocedure, are disclosed. In particular, if the WTRU uses acontention-based preamble, such method may be necessary because an eNBmay not know the identity of the WTRU. For example, the WTRU may use acontention-based preamble in the case of contention-based random access(CBRA).

Alternative examples are disclosed in cases where a dedicated preambleis used on SCells, for example, in the case of contention free randomaccess (CFRA). In those examples, uplink timing synchronization may beobtained without the need for the WTRU to monitor the CSS of an SCell,in particular, if the preamble transmission is initiated in a mannerthat is known and/or controlled by the eNB. For example, by reception ofa PDCCH DCI that orders the WTRU to perform at least a preambletransmission on the uplink of an SCell.

Examples of the WTRU obtaining uplink timing alignment for one or moreSCells are disclosed. For example, the SCells may be configured uplinkresources. This may include, more generally, how a WTRU may perform aRACH procedure, or a variant of the R10 RACH procedure, or at least apreamble transmission on an SCell and a proper determination that theprocedure is completed for the preamble transmission.

For example, the WTRU may perform a procedure that includes at least oneof the following steps to gain uplink timing synchronization: initiationof the procedure, preamble transmission, preamble retransmissions, ifsupported, and completion of the procedure. Details of each step to gainuplink timing synchronization are described below.

A WTRU may initiate a procedure involving the transmission of apreamble, such as RACH procedure, a variant thereof, or a procedure togain uplink timing alignment, either autonomously or in response toreception of control signaling.

If initiated autonomously, the WTRU may use a dedicated preamble and aphysical random access channel (PRACH) mask index from an RRCconfiguration in case of a CFRA or a variant thereof. The WTRU may alsouse a medium access control (MAC) entity to select a preamble using theconventional LTE R8+ preamble selection methods in case of a CBRA or avariant thereof is used.

In a network-controlled preamble transmission, the WTRU may initiate theprocedure upon receipt of control signaling from an eNB. The WTRU mayreceive the control signaling from the eNB on the PDCCH of the concernedSCell or cross-carrier scheduled. For example, the concerned S Cell maybe an S Cell with configured uplink resources and configured PRACHresources. For example, the cross-carrier scheduled may be on the PDCCHof another serving cell, for example, PCell.

FIG. 2 is an example flow diagram of a network-controlled preambletransmission. The WTRU may first receive control signaling from thenetwork at 210. The control signaling may be a specific DCI 220, amedium access control (MAC) protocol data unit (PDU) 230, or an RRC PDU240. The WTRU may then determine the applicable SCell at 250. Once theapplicable SCell is determined, the WTRU may implicitly activate theSCell at 260 or initiate a preamble transmission at 270.

The WTRU may initiate a preamble transmission according to at least oneof the following methods:

The WTRU may receive a specific DCI, for example, a PDCCH order toperform a preamble transmission, by decoding a DCI format 1A, bydecoding a DCI format scrambled with the WTRU's Cell-RNTI (C-RNTI), orby decoding a DCI format scrambled with an SCell- (or TAG-) specificRNTI, which indicates on which SCell (or which TAG) the procedure may beperformed. The DCI may include a dedicated preamble, a PRACH mask indexapplicable to the concerned S Cell.

The DCI may indicate that the preamble transmission is for obtaininguplink timing synchronization.

The DCI may include a carrier indication field (CIF) which may be usedto determine the identity of the S Cell on which uplink resources thepreamble is transmitted.

The DCI may include an indication of whether the preamble transmissionis an initial transmission, a retransmission, or alternatively to whatretransmission in a sequence of preamble transmission the retransmissionshould correspond. For example, an initial transmission may be codepoint0, a retransmission may be codepoint 1, and a sequence of preambletransmission the retransmission corresponds to may be codepoint 01, 10,11 in the case of, at most, three retransmissions. For example, thereceived codepoint may correspond to PREAMBLE_TRANSMISSION_COUNTER+1.

The DCI may include an indication of power settings, for example,according to a sequence of transmissions as disclosed above, or anindication to increase by some power step the preamble transmit powerfrom either a previous preamble transmission attempt or from apre-defined value.

The DCI may include a CIF field, in case of cross-carrier scheduling,which may indicate a serving cell with configured uplink resources forwhich the request for a preamble transmission applies. Alternatively,the DCI may include a CIF field which may indicate a serving cell aspart of a secondary TAG for which the request for a preambletransmission applies, for example, for gaining uplink timing alignmentmay be applied.

The DCI may indicate a maximum number of autonomous preambleretransmissions for the procedure, if autonomous preambleretransmissions are allowed. For example, an allowed autonomousretransmission may be an autonomous retransmission following the end ofa window during which the WTRU has not met the conditions for thecompletion of the procedure or at expiration of a retransmission timer.

The DCI may indicate whether or not the preamble may be considered as aninitial preamble transmission or as a preamble retransmission.

The WTRU may receive a MAC PDU including control signaling that triggersthe initiation of the procedure. The MAC PDU may include a MACactivation/deactivation CE that activates an SCell for which thecorresponding TA timer is stopped or expired. The MAC PDU may include aMAC control element (CE) that triggers the transmission of a preamble,for example, for gaining uplink timing for an SCell with configureduplink resources. The MAC CE may include a dedicated preamble and aPRACH mask index applicable to the concerned SCell. The MAC CE mayinclude an indication for the WTRU to determine the identity of theSCell on which uplink resources the preamble may be transmitted. Forexample, the indication may be either a flag in a bitmap, a cell indexfield or based on the activation state of the S Cells.

The MAC PDU may indicate that the preamble transmission may be forobtaining uplink timing synchronization. The MAC CE may include anindication of whether the preamble transmission is an initialtransmission, a retransmission, or alternatively to what retransmissionin a sequence of preamble transmissions the retransmission shouldcorresponds. For example, an initial transmission may be codepoint 0, aretransmission may be codepoint 1, and a sequence of preambletransmission the retransmission corresponds to may be codepoint 01, 10,11 in the case of at most three retransmissions. For example, thereceived codepoint may correspond to PREAMBLE_TRANSMISSION_COUNTER+1.The MAC CE may include an indication of power settings, for example,according to a sequence of transmissions as disclosed above, or anindication to increase by some power step the preamble transmit powerfrom either a previous preamble transmission attempt or from apre-defined value. The MAC CE may indicate a maximum number ofautonomous preamble retransmissions for the procedure, if autonomouspreamble retransmissions are allowed. For example, an allowed autonomousretransmission may be an autonomous retransmission following the end ofa window during which the WTRU has not met the conditions for thecompletion of the procedure, or at expiration of a retransmission timer.The MAC CE may indicate whether or not the preamble may be considered asan initial preamble transmission or as a preamble retransmission.

The WTRU may receive an RRC PDU including control signaling thattriggers the initiation of the procedure, for example, upon addition ofthe SCell to the WTRU configuration. The RRC PDU may include a dedicatedpreamble and a PRACH mask index applicable to the concerned SCell. TheRRC PDU may indicate that the preamble transmission may be for obtaininguplink timing synchronization. The RRC PDU may include an indication ofwhether the preamble transmission is an initial transmission, aretransmission, alternatively to what retransmission in a sequence ofpreamble transmissions the retransmission corresponds. For example, aninitial transmission may be codepoint 0, a retransmission may becodepoint 1, and a sequence of preamble transmission the retransmissioncorresponds to may be codepoint 01, 10, 11 in the case of at most threeretransmissions. For example, the received codepoint may correspond toPREAMBLE_TRANSMISSION_COUNTER+1. The RRC PDU may include an indicationof power settings, for example, according to a sequence of transmissionsas disclosed above, or an indication to increase by some power step thepreamble transmit power from either a previous preamble transmissionattempt or from a pre-defined value. The RRC PDU may indicate a maximumnumber of autonomous preamble retransmissions for the procedure, ifautonomous preamble retransmissions are allowed. For example, an allowedautonomous retransmission may be an autonomous retransmission followingthe end of a window during which the WTRU has not met the conditions forthe completion of the procedure, or at expiration of a retransmissiontimer. Alternatively, the preamble transmission may be triggered if theSCell is not considered synchronized. For example, the SCell may not besynchronized if the TAT corresponding to the S Cell is either stopped orexpired.

The control signaling described above may be received on the PDCCH ofthe concerned S Cell. For example, the concerned S Cell may be eitherthe S Cell on which uplink resource the WTRU may transmit a preamble oranother S Cell of the same TA group which may trigger a preamble onanother SCell (with configured PRACH resources) of the correspondingTAG.

Alternatively, the WTRU may receive any of the above control signalingby cross-carrier scheduling on any downlink serving cell of the WTRU.The reception of any of the above control signaling may implicitlyactivate the SCell (with configured PRACH resources) on which uplinkresources the preamble may be transmitted, or all other SCells of thesame TAG for which at least one SCell has a valid PRACH configuration.

Any of the above control signaling schemes may trigger the procedure fora plurality of SCells (with configured uplink and PRACH resources), oralternatively for at least one such SCell for each TAG (possibly for oneor more secondary TAG).

In one example, the WTRU may decode a PDCCH scrambled with the C-RNTI ofthe WTRU. The WTRU may then determine that it received a DCI indicatingthat a procedure to gain uplink timing alignment may be performed. Forexample, the DCI indicator may be performed may be either a RACHprocedure or a preamble transmission. The PDCCH may be either on anactivated SCell, if configured to receive and decode PDCCH on the SCell,or on a PCell if configured for cross-carrier scheduling and if theconcerned S Cell is activated. For example, in the case of CFRA, a DCIformat 1A may be used including a dedicated preamble and a PRACH maskindex. The DCI may include an indication that the preamble transmissionis an initial preamble transmission for the procedure or aretransmission.

In R8+, the following is used to determine the transmission power forthe preamble on the PCell where at leastpreamblelnitialReceivedTargetPower and powerRampingStep may be providedby higher layer signaling.

A preamble transmission power PPRACH may be determined as:PPRACH=min{Pcmax,c(i), PREAMBLE_RECEIVED_TARGET_POWER+PLc}_[dBm], wherePcmax,c(i) is the configured WTRU transmit power for subframe i of theprimary cell and PLc is the downlink pathloss estimate calculated in theWTRU for the primary cell.

The random-access procedure may be performed as follows: setPREAMBLE_RECEIVED_TARGET_POWER topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.The physical layer may then be instructed to transmit a preamble usingthe selected PRACH, corresponding RA-RNTI, preamble index andPREAMBLE_RECEIVED_TARGET_POWER.

FIG. 3 shows example methods for preamble transmissions. The necessaryparameters may be configured by higher layers for S Cells as part of theRACH configuration of the SCell. If after receiving control signalingfrom the network at 310, the WTRU determines, for example, using anyexample disclosed above, that it needs to initiate a procedure for thetransmission of a preamble at 320, the WTRU may perform at least one ofthe following.

The WTRU may determine the proper power settings according to an initialpreamble transmission at 330 based on at least one of the following:downlink pathloss reference 332; PREAMBLE_TRANSMSSION_COUNTER−1 334; novalid pathloss measurement 336; and radio link quality 338. The powersetting may be set according to the downlink pathloss reference at 332.The downlink pathloss reference may be either the corresponding S CellDL of the SCell UL used for the transmission of the preamble, any SCellDL of the TAG of the SCell for which the SCell UL is used for thetransmission of the preamble, or a DL configured using RRC signaling.

The power setting may be set according to thePREAMBLE_TRANSMISSION_COUNTER−1 334. The PREAMBLE_TRANSMISSION COUNTER−1may be derived from the control signaling that triggered the preambletransmission. For example, the counter may either be the received valueor the received value+1. An initial transmission may use the receivedvalue [0]+1 in the control signaling. The WTRU may not apply any powerramping for the S Cell, in particular, if the WTRU is not allowed toperform any autonomous preamble retransmissions or preambleretransmissions may be eNB controlled.

If the WTRU has no valid pathloss measurement 336 for the pathloss (PL)reference used for the preamble transmission, the WTRU may determinethat the transmission of a preamble may not be performed. If the WTRUdetermines that it experiences a low radio link quality 338, either onthe associated S Cell DL or on the downlink of the serving cell used aspathloss reference, the transmission of a preamble may not be performed.For example, the radio link problems may be based on a radio linkmanagement (RLM) procedure. For example, the associated SCell DL may bethe system information block 2 (SIB2)-linked SCell DL as per thesemi-static configuration of the WTRU.

The WTRU may determine 370 the preamble and PRACH resource for theinitial preamble transmissions, according to at least one of thefollowing. If a dedicated preamble and a PRACH mask index was received372 in the control signaling that initiated the preamble transmission,the WTRU may transmit the preamble in the indicated PRACH resource.Otherwise, if a dedicated preamble and a PRACH mask index are configured374 by RRC for the concerned SCell, the WTRU may transmit the preamblein the indicated PRACH resource. Otherwise, the WTRU may either select376 a preamble and initiate a contention-based RACH procedure, or stopthe procedure 378. For example, the procedure may be stopped in the caseof a false alarm or an error case. In particular, the WTRU may stop theprocedure in the case that CBRA is not supported for the procedure onSCells.

The WTRU may determine 350 the subframe in which the preambletransmission may be performed. The preamble transmission may beperformed at the first available occasion 352, after a fixed delay 354corresponding to a WTRU processing time, or corresponding to the timenecessary to complete activation of the corresponding SCell, if notactivated already. For example, according to R8+ timing of the PCell theWTRU may, if requested by higher layers, transmit random access preamblein the first subframe n+k2, k2>=6 where a PRACH resource is available.The timing of the PCell may also apply to the preamble transmission ofan SCell, when a random access procedure is initiated by a PDCCH orderin subframe n.

In another example, the WTRU may perform the preamble transmission inthe first subframe corresponding to n+8+k2, where k2≧0 and where a PRACHresource is available. For example, if the request for the transmissionof a preamble is received before the concerned SCell is activated fromreception of control signaling in subframe n, the WTRU may perform thepreamble transmission in the first subframe.

If the WTRU determines 340 that a preamble may be transmitted, the WTRUmay perform 342 the preamble transmission in the corresponding resourceusing the corresponding power settings. The WTRU may start 360 a windowtimer, such as a TAResponseWindow, which may be the RAR windowra-ResponseWindowSize, during which it may expect to complete theprocedure.

If the preamble (re)transmission coincides with another scheduled uplinktransmission, the WTRU may either scale back the power of the preambletransmission, or alternatively postpone the preamble (re)transmission toa subsequent occasion.

FIG. 4 is an example of options for handling or avoiding SCell preamblecollisions with other uplink transmissions. The preamble(re)transmission coinciding or “colliding” with another uplinktransmission may mean that the subframe in which the preamble would betransmitted is the same subframe in which another uplink transmissionwould be made. The preamble (re)transmission coinciding with anotheruplink transmission may mean that the subframe in which the PRACHcarrying the preamble would be transmitted is the same subframe in whichanother uplink transmission would be made. Postponing the preamble(re)transmission to a subsequent occasion may mean that the WTRU selectsanother, maybe later, PRACH.

In FIG. 4, the WTRU may decide to (re)transmit a preamble on an SCell at400. The WTRU may then select a PRACH subframe and PRACH at 405. TheWTRU may then determine whether there will be a collision such as one ofthe possible collisions shown in FIG. 5 at 410. If there is going to bea possible collision then the WTRU may postpone the preambletransmission to a later subframe at 415. If there is no collisionexpected, then the physical (PHY) layer of the WTRU may determinewhether there will be a collision with another UL transmission in thePRACH subframe at 435. If the PHY layer determines there will be nocollision, the WTRU may transmit the preamble using the selected PRACHsubframe and PRACH at 450. If the PHY layer determines that there willbe a collision, the PHY layer may cancel the SCell PRACH transmission at440. The PHY layer may then inform the higher layers of the WTRU of thecancellation at 445. As an alternative, if there is no collisionexpected at 410, the WTRU may transmit the preamble using the selectedPRACH subframe and PRACH at 450.

The WTRU may select a PRACH subframe and PRACH to avoid a collision witha scheduled UL transmission at 420. The WTRU may then transmit thepreamble using the selected PRACH subframe and PRACH at 450. As analternative, after selection of the PRACH subframe and PRACH at 420, thePHY layer of the WTRU may determine whether there will be a collisionwith another UL transmission in the PRACH subframe at 435. If the PHYlayer determines there will be no collision, the WTRU may transmit thepreamble using the selected PRACH subframe and PRACH at 450. If the PHYlayer determines that there will be a collision, the PHY layer maycancel the SCell PRACH transmission at 440. The PHY layer may theninform the higher layers of the WTRU of the cancellation at 445.

The WTRU may select a PRACH subframe and PRACH to avoid a selection thatmay collide with one or more of the possibilities listed in FIG. 6 at425. The WTRU may then transmit the preamble using the selected PRACHsubframe and PRACH at 450. As an alternative, after selection of thePRACH subframe and PRACH at 425, the PHY layer of the WTRU may determinewhether there will be a collision with another UL transmission in thePRACH subframe at 435. If the PHY layer determines there will be nocollision, the WTRU may transmit the preamble using the selected PRACHsubframe and PRACH at 450. If the PHY layer determines that there willbe a collision, the PHY layer may cancel the SCell PRACH transmission at440. The PHY layer may then inform the higher layers of the WTRU of thecancellation at 445.

The higher layers of the WTRU, for example, a MAC layer, may select aPRACH subframe and PRACH at 430. The physical (PHY) layer of the WTRUmay determine whether there will be a collision with another ULtransmission in the PRACH subframe at 435. If the PHY layer determinesthere will be no collision, the WTRU may transmit the preamble using theselected PRACH subframe and PRACH at 450. If the PHY layer determinesthat there will be a collision, the PHY layer may cancel the S CellPRACH transmission at 440. The PHY layer may then inform the higherlayers of the WTRU of the cancellation at 445.

FIG. 5 shows examples of the conditions for which the WTRU may postponeSCell preamble re(transmissions) to a subsequent occasion. The WTRU maypostpone the preamble (re)transmission to a subsequent occasion if oneor more of the following applies: The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 510 with ascheduled UL transmission on the concerned SCell. The WTRU may postponethe preamble (re)transmission if the preamble (re)transmission coincides515 with a scheduled UL transmission on the PCell. The WTRU may postponethe preamble (re)transmission if the preamble (re)transmission coincides520 with a scheduled UL transmission on any serving cell. The WTRU maypostpone the preamble (re)transmission if the preamble (re)transmissioncoincides 525 with a scheduled UL transmission on any serving cell inthe same band as the concerned SCell. The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 530 with anytype of scheduled UL transmission. The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 535 with aspecific type of UL transmission such as ACK/NACK transmission. The WTRUmay postpone the preamble (re)transmission if the preamble(re)transmission coincides 540 with a specific type of UL transmissionsuch as a PUCCH transmission. The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 545 with aspecific type of transmission such as periodic SRS transmission.Alternatively, when PRACH transmission coincides with periodic SRStransmission in a subframe, the PRACH may be transmitted and the SRStransmission may be dropped. The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 550 with aspecific type of transmission such as aperiodic SRS transmission.Alternatively, when PRACH transmission coincides with an aperiodic SRStransmission in a subframe, the PRACH may be transmitted and the SRStransmission may be dropped. The WTRU may postpone the preamble(re)transmission if the preamble (re)transmission coincides 555 with aspecific type of UL transmission such as periodic CSI transmission.Alternatively, when PRACH transmission coincides with periodic CSItransmission, the PRACH may be transmitted and the periodic CSI may bedropped. The WTRU may postpone the preamble (re)transmission if thepreamble (re)transmission coincides 560 with a specific UL transmissionsuch as a PRACH scheduled for transmission on another serving cell.

When selecting a PRACH, the WTRU may take into account scheduled uplinktransmissions and avoid selecting a PRACH that collides with a scheduleduplink transmission. For example, the WTRU may avoid selecting a PRACHin the same subframe as a scheduled uplink transmission. FIG. 6 showsexamples of transmissions a WTRU may avoid when selecting a PRACH. TheWTRU may avoid selecting a PRACH that may collide with one or more ofthe following: The WTRU may avoid selecting a PRACH that may collidewith a scheduled 610 UL transmission on the concerned SCell. The WTRUmay avoid selecting a PRACH that may collide with a scheduled 615 ULtransmission on the PCell. The WTRU may avoid selecting a PRACH that maycollide with a scheduled 620 UL transmission on any serving cell. TheWTRU may avoid selecting a PRACH that may collide with a scheduled 625UL transmission on any serving cell in the same band as the concernedSCell. The WTRU may avoid selecting a PRACH that may collide with anytype of scheduled 630 UL transmission. The WTRU may avoid selecting aPRACH that may collide with a specific type of UL transmission 635 suchas ACK/NACK transmission. The WTRU may avoid selecting a PRACH that maycollide with a specific type of UL transmission 640 such as a PUCCHtransmission. The WTRU may avoid selecting a PRACH that may collide witha specific type of transmission 645 such as periodic SRS transmission.The WTRU may avoid selecting a PRACH that may collide with a specifictype of transmission 650 such as an aperiodic SRS transmission. The WTRUmay avoid selecting a PRACH that may collide with a specific type of ULtransmission 655 such as periodic CSI transmission. The WTRU may avoidselecting a PRACH that may collide with a specific UL transmission 660such as a PRACH scheduled for transmission on another serving cell.

The decision to postpone the preamble (re)transmission to a subsequentoccasion may be performed by higher layers in the WTRU. The decision topostpone the preamble transmission may be made by the WTRU when it isknown in advance that an UL transmission is scheduled to occur in acertain subframe or subframes. Avoiding selection of a PRACH that maycollide with another uplink transmission occasion may be performed byhigher layers in the WTRU. The WTRU may avoid selection of a PRACH thatmay collide with another uplink transmission when it is known in advancethat UL transmission is scheduled to occur in a certain subframe orsubframes. As an example, higher layers in the WTRU may be or mayinclude the MAC layer.

The decision to postpone the preamble (re)transmission may be performedby the WTRU at the physical layer. For example, the WTRU PHY layer maypostpone or decided to postpone the preamble (re)transmission, if afterthe higher layers (e.g., the MAC) provide a PRACH resource to thephysical layer, an UL transmission is scheduled such as in response toan UL or DL grant (e.g., ACK/NACK). The WTRU physical layer maydetermine that PRACH transmission is not possible in the designatedsubframe, for example, due to a collision with another UL transmissionand may cancel the PRACH transmission.

The WTRU physical layer may inform the higher layers that PRACHtransmission is not possible in a designated subframe. The physicallayer may inform the higher layers that the PRACH transmission wascancelled. The WTRU, for example, he higher layers of the WTRU, maychoose another PRACH resource if PRACH transmission was cancelled. Forexample, the higher layers may be or may include the MAC layer. When aPRACH transmission is cancelled, the WTRU may choose another PRACHresource without updating one or more of the timers and countersrelating to the random access procedure such as thePREAMBLE_TRANSMISSION_COUNTER.

The WTRU may maintain a counter to keep track of the consecutive numberof times the PRACH transmission is cancelled. The WTRU may maintain atimer to keep track of how long the WTRU is unable to transmit the PRACHdue to collisions with other uplink transmissions. If the WTRU is unableto transmit the PRACH after a number of attempts, for example, based onthe counter counting the number of cancellations, or after a period oftime, due to collisions with other uplink transmissions, the WTRU maycease attempting to transmit the PRACH and may inform the eNB viasignaling, such as via RRC or MAC signaling. This may, for example, beapplicable when the eNB had requested the WTRU to perform a randomaccess procedure for example for the purpose of timing alignment.

The WTRU may postpone the PRACH transmission if WTRU maximum power wouldbe exceeded in the subframe in which the PRACH is to be transmitted. TheWTRU may determine the required transmit power for each channel to betransmitted in a given subframe; and if in that subframe there is aPRACH scheduled to be transmitted, the WTRU may do one or more of thefollowing. The WTRU may determine if the WTRU maximum allowed transmitpower would be exceeded if all channels were transmitted simultaneouslyincluding the PRACH. If the WTRU maximum allowed transmit power would beexceeded and a PRACH transmission is scheduled, the WTRU may cancel thePRACH transmission. If the PRACH transmission is cancelled, the WTRU maydetermine if the maximum WTRU power would be exceeded for the scheduledchannels excluding the PRACH and proceed with scaling as needed based onthe scheduled channels other than the PRACH. The WTRU maximum allowedtransmit power may be the WTRU maximum configured output power, Pcmax,as defined in LTE. The WTRU maximum allowed output power may be the WTRUpower class power.

When the WTRU is transmitting in multiple bands, a determination as towhether maximum allowed transmit power would be exceeded may beperformed on an individual band basis instead of being performed on aWTRU basis. The determination may also first be performed on anindividual band basis and then performed on a WTRU basis. Whenperforming the determination on an individual band basis, the maximumallowed power for the band may be used to determine whether the maximumallowed transmit power would be exceeded.

If the PRACH transmission coincides with another transmission and thesimultaneous transmission is permitted, if band and/or WTRU maximumoutput power would be exceeded, the WTRU may scale the power of thePRACH based on its priority relative to the other channels beingtransmitted. In the R10 channel prioritization, a PUCCH has the highestpriority, a PUSCH with a UCI has the next highest priority, and a PUSCHwithout a UCI has the lowest priority.

A PRACH may be given a priority such that one or more of the followingapplies. A PRACH may be transmitted if there is available power afterpower is allocated to channels with higher priority. If after power isallocated to higher priority channels, there is not enough power totransmit the PRACH without scaling, the PRACH may be scaled. If afterpower is allocated to higher priority channels, there is not enoughpower to transmit the PRACH without scaling, the PRACH transmission maybe cancelled. If PRACH transmission is cancelled, the remaining lowerpriority channels, may be transmitted with power allocation and scalingas needed. If PRACH is scaled, the remaining lower priority channels,may be dropped.

In one example, a PRACH may have the next highest priority after a PUSCHwith a UCI. In this example, if maximum power may be exceeded, (bandand/or WTRU maximum output power), and if all channels scheduled to betransmitted in a subframe were to be transmitted, one or more of thefollowing may apply. Power may first be allocated to any PUCCH. Afterallocation of power to any PUCCH, any remaining power may be allocatedto PUSCH with UCI. If there is not enough power for PUSCH with UCI, thePUSCH with UCI may be scaled and no other channels would be transmitted.In this case, the PRACH may be cancelled. If there is remaining powerafter allocation to any PUCCH and PUSCH with UCI, power may be allocatedto any PRACH. If there is not enough power for any PUCCH plus any PUSCHwith UCI plus PRACH, the PRACH may be scaled and any PUSCH without UCImay not be transmitted. If there is not enough power for any PUCCH plusany PUSCH with UCI plus PRACH, the PRACH transmission may be cancelled.If PRACH transmission is cancelled, PUSCH without UCI, may betransmitted with power allocation and scaling as needed. If there ispower remaining after allocating power to PRACH, PUSCH without UCI maybe transmitted with scaling if needed.

Power allocation and/or scaling may be performed on a band basis and/ora WTRU basis.

FIG. 7 shows an example of the WTRU using a dedicated preamble and PRACHmask index to perform preamble transmission on the S Cell. In oneexample, the WTRU may receive 710 control signaling from the network.The WTRU may also receive 720 a dedicated preamble and PRACH mask in aPDCCH order in subframe n. The WTRU may use 730 the dedicated preambleand a PRACH mask index received in a PDCCH order in subframe n toperform the preamble transmission on the SCell. The WTRU may determine740 from the received control signaling, for example, codepoint 0, thatthe request is for an initial preamble transmission and sets 750 thepreamble counter to 1, thereby the WTRU may not apply any power ramping.The WTRU may use 760 the corresponding S Cell DL as the PL reference,and perform 770 the uplink transmission in the first subframe n+k2, k2≧6where a PRACH resource is available.

The WTRU may determine that a preamble may be retransmitted according toat least one of the following methods. The WTRU receives controlsignaling, which indicates that the preamble transmission is for aretransmission. The WTRU may autonomously initiate the retransmission ofa preamble, for example upon failure to complete the procedure accordingto the embodiments described below. The WTRU may start a window timer,for such as, a TAResponseWindow, which may be the RAR windowra-ResponseWindowSize, during which it may expect to complete theprocedure.

In one example, a WTRU may not be allowed to autonomously perform anypreamble retransmissions on the uplink resources of an SCell. A WTRU mayperform a preamble retransmission when initiated by reception of controlsignaling. In another example, the WTRU may autonomously performpreamble retransmission for an SCell. The WTRU may autonomously performpreamble retransmission up to a maximum number of attempts if, followingan initial preamble transmission, the WTRU has not received after aspecific amount of time any time advance command (TAC) or any uplinkgrant for an SCell within the TAG of the SCell on which the preamble wastransmitted.

When the WTRU performs a preamble retransmission, it may apply powerramping. For autonomous retransmissions, the power ramping may beapplied similarly to that of the PCell, for example, using a counter tocount the number of attempts. For retransmission requested by the eNBusing control signaling, the WTRU may apply a stepwise increase if thecontrol signaling indicates that the WTRU needs to ramp-up the power,use a counter of the number of attempts, or use an indication in thecontrol signaling to determine the exact power ramping to apply. Thecounter of the number of attempts may be reset to its initial value whenthe WTRU initiates the first transmission of a preamble for theprocedure. The counter of the number of attempts may also be reset toits initial value upon deactivation of the corresponding SCell, uponactivation of the corresponding SCell, upon configuration orreconfiguration of the corresponding SCell, upon configuration orreconfiguration of the TAG of the S Cell, or when the procedurecompletes successfully. The power ramping may be limited up to a maximumvalue.

FIG. 8 is an example of a network-controlled dedicated preambleretransmission. The WTRU may determine 810 that the initial preambletransmission was not successful, for example, based on the expiration ofthe window, for example, a TAResponse-window, and may have discarded thededicated preamble and PRACH mask index used for the initial preambletransmission. The WTRU may maintain 820 a preamble counter of the numberof preamble transmissions since the initial attempt for the TAG. TheWTRU may receive 830 in subframe n control signaling that includes adedicated preamble and a PRACH mask index which indicates that the WTRUperforms a preamble retransmission on the S Cell using the signaled(maybe different than for the previous transmission) dedicatedparameters. The WTRU may determine 840 from the control signaling, forexample, codepoint 1, that the request is for a preamble retransmissionand set 850 the preamble counter to the number of preamble transmissionsperformed so far for the TAG+1 (i.e., the counter is increased by oneunit for every preamble transmission until the counter is reset). TheWTRU may therefore apply 860 some power ramping. The WTRU may use 870the corresponding SCell DL as the PL reference, and perform 880 theuplink transmission in the first subframe n+k2, k2≧6 where a PRACHresource is available.

In another example of a network-controlled dedicated preambleretransmission, the WTRU may receive in subframe n control signalingthat includes a dedicated preamble and a PRACH mask index whichindicates that the WTRU performs a preamble retransmission on the S Cellusing the signaled (maybe different than for the previous preambletransmission) dedicated parameters. The WTRU may determine from thecontrol signaling, for example, codepoint, 2 that the request is for apreamble retransmission corresponding to a second retransmission in asequence of preamble transmissions performed for the TAG, independentlyof how many preamble transmissions actually took place since the WTRUhas initiated the procedure. The WTRU may then apply the power rampingthat corresponds to the preamble transmission in the sequence. The WTRUmay use the corresponding SCell DL as the PL reference, and perform theuplink transmission in the first subframe n+k2, k2≧6 where a PRACHresource is available and according to the PRACH mask index.

The WTRU may determine whether or not the procedure involving thetransmission of a preamble is complete. The procedure may be for gaininguplink synchronization, an RACH procedure, or any of the proceduresincluding one of the examples described above. The WTRU may determineeither the RACH procedure or the procedure for gaining uplink timingalignment has completed using the 3GPP R8+ methods. In particular, theWTRU may use the 3GPP r8+ methods in the case of a contention-basedprocedure on the S Cell.

Alternatively, the WTRU may determine that the procedure is completedaccording to the reception of RAR or other events not involving RAR. Thereception of the RAR may be considered, if the WTRU decodes a DCI in theCSS of the PDCCH of a serving cell. The WTRU may then be scheduled withan RAR from the reception of a PDCCH DCI on the CSS of a PCell, whichmay include the CIF of the corresponding S Cell (or an SCell in the sameTAG). The reception of the RAR may also be considered if the WTRU may bescheduled with an RAR from the reception of a PDCCH DCI on the CSS of anSCell. Alternatively, the reception of the RAR is counted for an SCellfor which the WTRU is configured with a RACH configuration.Alternatively, the reception of the RAR is counted while a timer isrunning, such as an RAR window which includes subframes after thetransmission of a preamble and until successful reception of the RAR orexpiration of the timer.

Other events for consideration of the procedure completion may betimer-based completion, maximum number of preamble retransmissions,reception of control signaling on PDCCH, reception of MAC controlsignaling, or contention resolution. For example, reception of controlsignaling on PDCCH may be reception of an uplink grant, reception of arequest for an aperiodic SRS transmission or reception of a DCIscrambled with a specific RNTI. For example, reception of MAC controlsignaling may be MAC TAC CE, MAC RAR, or other MAC CE. For example,contention resolution may be used if CBRA is used.

The completion of the procedure may be bound by the occurrence of atleast one of the above or until a specific time has elapsed, forexample, by a reception window, whichever comes first. For example, ifthe WTRU does not successfully complete the procedure during theallocated window, it may determine either that the procedure is notsuccessful and/or that the procedure has failed. In the case where theprocedure is determined not successful, the WTRU may perform anautonomous retransmission or perform no further actions. If theprocedure is not successful, the WTRU may perform an autonomousretransmission after a certain backoff or may deactivate one or moreSCells of the concerned TAG. In the case where the procedure has failed,the WTRU may discard the explicitly signaled dedicated preamble(ra-PreambleIndex) and PRACH mask index (PRACH-Mask-index), deactivateone or more SCells of the concerned TAG, or perform no further actions.The WTRU may keep the SCell(s) in their current activation state, andmay monitor the PDCCH for further control signaling that may order apreamble retransmission for the concerned SCell, or TAG.

The WTRU may restart the applicable TA timer where the procedurecompletes successfully. For example, the WTRU may restart the TA timerwhen a TAC is received in the transmission of a preamble, either in anRAR or in a MAC CE. The WTRU may reset a counter of preambletransmission to its initial value, for example reset to 0.

FIG. 9 is an example method to determine completion of thenetwork-controlled procedure. The WTRU may determine 910 that theprocedure is completed from the reception of a TAC using C-RNTI inWTRUSS. The WTRU may monitor 920 the CSS of the SCell during the RARwindow applicable to the transmitted preamble using RA-RNTI in CSS.Alternatively, the WTRU may monitor the CSS of the PCell during the RARwindow applicable to the transmitted preamble using RA-RNTI in CSS. TheWTRU may then determine 940 that the procedure is completed based on thereception of a TAC. The WTRU may determine 930 that the procedure iscompleted from the reception of an uplink grant for an uplink sharedchannel (UL-SCH) transmission on an SCell UL that is in the same TAG asthe SCell UL. After performing any one of steps 910, 930, or 940, theWTRU may then discard 950 the preamble and PRACH mask index received inthe control signaling that requested the preamble transmission. The WTRUmay reset 960 the preamble counter. The WTRU may then apply 970 thereceived TAC to all SCell UL o the concerned TAG. The WTRU may restart980 the TA timer applicable to the TAG and consider all uplink S Cellsof the TAG time-synchronized with the network.

In one example, the WTRU may determine that the procedure is completedfrom the reception of a TAC. The WTRU may receive the TAC in a MAC PDUas a MAC TAC CE that includes a TAC for the concerned TAG and scheduledusing a DCI scrambled with the WTRU's C-RNTI on the WTRUSS of the PDCCHof any activated serving cell. The WTRU may discard the dedicatedpreamble and PRACH-mask index received in the control signaling thatrequested the preamble transmission, and reset a preamble counter. TheWTRU may apply the received TAC to all SCell UL of the concerned TAG.The WTRU may restart the TA timer applicable to the TAG and consider alluplink SCells of the TAG time-synchronized with the network.

In another example, the WTRU may monitor the CSS of the SCell during theRAR window applicable to the transmitted preamble. The WTRU maydetermine that the procedure is completed from the reception of a TAC.The WTRU may receive the TAC in a MAC RAR that includes a TAC for theconcerned TAG and scheduled using a DCI scrambled with the WTRU'sRA-RNTI on the CSS of the PDCCH of any activated serving cell. The WTRUmay discard the dedicated preamble and PRACH-mask index received in thecontrol signaling that requested the preamble transmission, and resetthe preamble counter. The WTRU may apply the received TAC to all SCellUL of the concerned TAG. The WTRU may restart the TA timer applicable tothe TAG and considers all uplink S Cells of the TAG time-synchronizedwith the network.

In another example, the WTRU may determine that the procedure iscompleted from the reception of an uplink grant for an UL-SCHtransmission on an SCell UL that is in the same TAG as the SCell UL onwhich the dedicated preamble was transmitted. The WTRU may discard thededicated preamble and PRACH-mask index received in the controlsignaling that requested the preamble transmission, and reset thepreamble counter. The WTRU may restart the TA timer applicable to theTAG and consider all uplink SCells of the TAG time-synchronized with thenetwork.

For a preamble transmission on a PCell, the WTRU may perform RARreception. Once the Random Access Preamble is transmitted, regardless ofthe possible occurrence of a measurement gap, the WTRU may monitor thePDCCH of the PCell for Random Access Responses identified by theRA-RNTI. The WTRU may monitor the PDCCH in the RA Response window whichstarts at the subframe containing the end of the preamble transmissionplus three subframes and has a length of ra-ResponseWindowSizesubframes. The RA-RNTI associated with the PRACH in which the RandomAccess Preamble is transmitted, is computed as:

RA-RNTI=1+t _(—) id+10*f _(—) id  Equation (1)

where t_id is the index of the first subframe of the specified PRACH(0≦t_id<10), and f_id is the index of the specified PRACH within thatsubframe, in ascending order of frequency domain (0≦f_id<6). The WTRUmay stop monitoring for Random Access Responses after successfulreception of a Random Access Response containing Random Access Preambleidentifiers that matches the transmitted Random Access Preamble.

Upon reception of an RAR that corresponds to a preamble transmitted onan S Cell, the WTRU may determine that the procedure is successfullycompleted.

For an SCell, the WTRU may decode the PDCCH for a message 2 (msg2), forexample, an RAR or a MAC TAC CE, according to at least one of thefollowing. The WTRU may monitor for a DCI in the CSS of the PDCCH of thePCell DL. The WTRU may attempt to decode the DCI using a RA-RNTI. TheDCI may include a CIF for the cross-carrier scheduling of the RAR on thePDSCH of the cell corresponding to the CIF, for example, the S Cell onwhich the preamble was transmitted. For example, the DCI for RAR for thepreamble transmission on an SCell may be received on the PDCCH of thePCell scrambled using RA-RNTI.

The WTRU may monitor for a DCI in the WTRUSS of the PDCCH of the PCellDL. The WTRU may attempt to decode the DCI using the WTRU's C-RNTI. TheDCI may include a CIF for the cross-carrier scheduling of the msg2 onthe PDSCH of the cell corresponding to the CIF, for example, the S Cellon which the preamble was transmitted. For example, the DCI for RAR forthe preamble transmission on an S Cell may be received on the PDCCH ofthe PCell scrambled using the WTRU's C-RNTI. As another example, the DCIfor MAC TAC CE for the preamble transmission on an S Cell may bereceived on the PDCCH of the PCell scrambled using the WTRU's C-RNTI.

The WTRU may monitor for a DCI in a CSS of the PDCCH of an SCell DL. TheCSS may be defined in a similar manner as for the PDCCH of the PCell.The WTRU may attempt decoding for DCI during a specific number ofsubframes, for example, during the reception window of the RAR on thePDCCH of an SCell. The WTRU may attempt decoding for DCI for an RA-RNTI.The SCell DL may correspond to the SCell for which the preamble wastransmitted, or may correspond to any SCell of the same TAG as the SCellfor which the preamble was transmitted. The WTRU may attempt to decodethe DCI using an RA-RNTI. The DCI may include a CIF for thecross-carrier scheduling of the RAR on the PDSCH of the cellcorresponding to the CIF, for example, the S Cell on which the preamblewas transmitted. For example, the DCI for RAR for the preambletransmission on an SCell may be received on the PDCCH of an SCellscrambled using the RA-RNTI.

The WTRU may monitor for a DCI in a WTRUSS of the PDCCH of an S Cell DL.The S Cell DL may correspond to the S Cell for which the preamble wastransmitted, or may correspond to any SCell of the same TAG as the SCell for which the preamble was transmitted. The WTRU may attempt todecode the DCI using the WTRU's C-RNTI. The DCI may include a CIF forthe cross-carrier scheduling of the msg2 on the PDSCH of the cellcorresponding to the CIF, for example, the SCell on which the preamblewas transmitted. For example, the DCI for RAR for the preambletransmission on an S Cell may be received on the PDCCH of an SCellscrambled using the WTRU's C-RNTI. As another example, the DCI for MACTAC CE for the preamble transmission on an S Cell may be received on thePDCCH of an SCell scrambled using the WTRU's C-RNTI.

The DCI may be scrambled, either with the C-RNTI of the WTRU or with aRA-RNTI. The DCI may be scramble with the C-RNTI of the WTRU if the DCIis received in the CSS or WTRUSS of the corresponding PDCCH. The DCI maybe scrambled with a RA-RNTI if the DCI is received in the CSS of thecorresponding PDCCH. In particular, if CFRA is possible, the WTRU mayuse C-RNTI to decode a DCI pertaining to the msg2.

The WTRU may monitor a PDCCH for the RAR using specific aggregationlevels, for example, AL4 and AL8.

The RA-RNTI, if used, may be derived using at least one of thefollowing. The WTRU may derive the RA-RNTI at least in part using anindex of the first subframe of the specified PRACH, or the index of thespecific PRACH (similar to a case where the preamble transmission wouldhave been performed on the PCell UL). Alternatively, the RA-RNTI may bederived at least in part using an index of the serving cell on which thepreamble was transmitted. For example, this may be done by adding thevalue of the corresponding servCellIndex. Alternatively, the RA-RNTI maybe derived at least in part using an index of the TAG of the servingcell on which the preamble was transmitted. For example, this may bedone by adding the value of the corresponding ta-groupIndex.Alternatively, the RA-RNTI may be derived using an additional valueconfigured by RRC for the WTRU.

If a DCI is successfully decoded for a msg2 corresponding to an SCell,either on the PDCCH of the PCell or of the SCell, the DCI may include aCIF. The received DCI may cross-carrier the msg2, in particular, ifC-RNTI is used to schedule the msg2.

In the case of cross-carrier scheduling for RACH on the SCell, as thenumber of HARQ process bits are 3 bits, same size as for CIF, which arereserved in case of format 1A using RA-RNTI, instead of including the 3bit CIF field in the PDCCH, the reserved HARQ process number field maybe replaced with the 3 bit CIF. The WTRU may use the HARQ process bitsin the DCI format to determine to what SCell the received controlsignaling is applicable.

In LTE R8+, the MAC RAR is defined as follows: A MAC PDU includes a MACheader and zero or more MAC Random Access Responses (MAC RAR) andoptionally padding. The MAC header is of variable size.

A MAC PDU header includes one or more MAC PDU subheaders; each subheadercorresponding to a MAC RAR except for the Backoff Indicator subheader.If included, the Backoff Indicator subheader is only included once andis the first subheader included within the MAC PDU header.

The MAC header may be of variable size and includes the followingfields: E, T, R, BI, and RAPID. E may be the Extension field wherein aflag indicates if more fields are present in the MAC header or not. TheE field may be set to “1” to indicate at least another set of E/T/RAPIDfields follows. The E field may be set to “0” to indicate that a MAC RARor padding starts at the next byte.

T may be the Type field wherein a flag indicates whether the MACsubheader contains a Random Access ID or a Backoff Indicator. The Tfield may be set to “0” to indicate the presence of a Backoff Indicatorfield in the subheader (BI). The T field may be set to “1” to indicatethe presence of a Random Access Preamble ID field in the subheader(RAPID).

R may be the Reserved bit, set to “0”. BI may be the Backoff Indicatorfield that identifies the overload condition in the cell. The size ofthe BI field may be 4 bits. RAPID may be the Random Access PreambleIDentifier field that identifies the transmitted Random Access Preamble.The size of the RAPID field may be 6 bits. The MAC header and subheadersare octet aligned.

FIG. 10 is an example E/T/RAPID MAC subheader. A MAC PDU subheader mayconsist of the three header fields E/T/RAPID as illustrated in FIG. 10.Octet 1 in FIG. 10 includes three header fields E 1001, T 1002, andRAPID 1003. FIG. 11 is an example E/T/R/R/BI MAC subheader. A MAC PDUsubheader may consist of three header fields, but for the BackoffIndicator (BI) subheader which includes the five header field E/T/R/R/BIas illustrated in FIG. 11. Octet 1 in FIG. 11 includes five headerfields, E 1101, T 1102, R 1103, R 1103, and BI 1104.

FIG. 12 is an example MAC RAR. A MAC RAR may include the four fieldsR/Timing Advance Command/UL Grant/Temporary C-RNTI as illustrated inFIG. 12. The timing Advance Command field may indicate the index value,T_(A) (0, 1, 2, . . . 1282), used to control the amount of timingadjustment that the WTRU may have to apply. The size of the TimingAdvance Command field may be 11 bits. The UL Grant field may indicatethe resources to be used on the UL. The size of the UL Grant field maybe 20 bits. The Temporary C-RNTI field may indicate the temporaryidentity that is used by the WTRU during Random Access. The size of theTemporary C-RNTI field may be 16 bits.

Octet 1 in FIG. 12 includes R 1201 and Timing Advance Command 1202.Octet 2 in FIG. 12 includes Timing Advance Command 1203 and UL Grant1204. Octet 3 in FIG. 12 includes UL Grant 1205. Octet 4 in FIG. 12includes UL Grant 1206. Octet 5 in FIG. 12 includes Temporary C-RNTI1207. Octet 6 in FIG. 12 includes Temporary C-RNTI 1208. Padding mayoccur after the last MAC RAR. Presence and length of padding is implicitbased on TB size, size of MAC header and number of RARs.

A MAC PDU for RAR may additionally include at least one of thefollowing: an identity of the SCell for which the RAR is applicable or aTAG identifier of the SCell for which the RAR is applicable. Theidentity of the SCell may be WTRU-specific, for example, it maycorrespond to the servCellIndex or it may correspond to the CIF. Theidentity of the SCell may be cell-specific such as a cell identity. Theidentity of a TAG identifier may be WTRU-specific, for example, it maycorrespond to a configured TAG identity.

For example, a WTRU may receive a MAC PDU containing an RAR with anidentity of the SCell for which the RAR is applicable. The MAC PDU maybe cross-scheduled on the PDCCH of the PCell using a DCI scrambled withthe WTRU's C-RNTI. Alternatively, the MAC PDU may be scheduled using aDCI scrambled with a RA-RNTI.

The WTRU may use a window or a timer during which it expects receptionof control signaling that completes the procedure. Upon expiration ofthe timer, if the WTRU has not received any such control signaling, theWTRU may determine that a preamble retransmission may be performed, ifWTRU-autonomous retransmission are allowed. Alternatively, the WTRU maydetermine that the procedure has completed. For example, the WTRU maydetermine that the procedure was either unsuccessful or has failed.

If the WTRU performs preamble retransmission for an SCell, eitherautonomously or under the control of the eNB, and the WTRU determinesthat it has reached the maximum number of preamble transmissions withoutsuccessfully completing the procedure, the WTRU may determine that theprocedure is either unsuccessful or has failed. The maximum number ofpreamble transmissions may be configured by higher layers.

The WTRU may determine that the procedure is successful upon receptionof control signaling on PDCCH. Upon reception of control signaling onPDCCH that corresponds to a preamble transmitted on an SCell, the WTRUmay determine that the procedure is successfully completed.

The WTRU may determine that the procedure is successful if the WTRUreceives a grant for an uplink transmission on an S Cell of the TAG thatcorresponds to the S Cell UL on which the preamble was transmitted. Forexample, reception of a DCI format indicating an uplink transmission,which may be received either on the PDCCH of the SCell or on anotherserving cell using cross-carrier scheduling. The DCI format may beformat 0. The WTRU may determine that the procedure is successful if theWTRU receives a request for an aperiodic SRS on an S Cell of the TAGthat corresponds to the SCell UL on which the preamble was transmitted.For example, a reception of the request may be received either on thePDCCH of the SCell or on another serving cell using cross-carrierscheduling.

The WTRU may determine that the procedure is completed upon receipt of arequest for initiating the transmission of a preamble on another SCellof the TAG that corresponds to the S Cell UL on which the preamble wastransmitted. In particular, the WTRU may determine the procedure issuccessful upon receipt of any of the above case where a dedicatedpreamble is used for the transmission of a preamble on an SCell. TheWTRU may determine that the procedure is successful, if the controlsignaling indicating an uplink transmission is received in the timespecified for the completion of the procedure, for example, a window.

The WTRU may determine that the procedure is successful if the WTRUreceives a DCI format scrambled with the WTRU's C-RNTI for the S Cell.The WTRU may determine that the procedure is successful if the WTRUreceives a DCI format scrambled with the RA-RNTI that corresponds to thepreamble transmitted for the SCell. The WTRU may determine that theprocedure is successful if the WTRU receives a DCI format scrambled witha specific RNTI, which RNTI indicates termination of the procedure, forexample a TA-RNTI. In particular the WTRU may determine that theprocedure is successful where a dedicated preamble is used for thetransmission of a preamble on an SCell, or if the control signalingindicates an uplink transmission is received in the time specified forthe completion of the procedure. For example, the time specified for thecompletion of the procedure may be a window. The control signaling mayindicate to the WTRU that the eNB has successfully received thetransmitted preamble.

The WTRU may determine that the procedure is successful upon receptionof MAC control signaling. The WTRU may determine that the procedure issuccessful upon reception of a MAC PDU that contains at least a TACapplicable to the SCell and/or TAG of the S Cell for which a preamblewas transmitted. For example, a TAC applicable to the S Cell may beinside a MAC TAC CE control element or inside a MAC RAR. The MAC PDU maybe received on the PDSCH of an SCell DL that is part of the concernedTAG, for example, the PDSCH of the SCell DL that corresponds to theSCell UL on which the preamble was transmitted, or on the PDSCH of anyserving cell. The WTRU may determine that the procedure is successfulupon reception of MAC control signaling in case a dedicated preamble isused for the transmission of a preamble on an SCell. For example, if thecorresponding MAC control signaling is received in the time specifiedfor the completion of the procedure, for example, a window. Uponreception of MAC control signaling that corresponds to a preambletransmitted on an SCell, the WTRU may determine that the procedure issuccessfully completed.

If the WTRU is allowed to transmit a preamble that is selected by theMAC, such as a contention-based procedure, the WTRU may determine thatthe procedure is successful according to similar criterion as for thecontention-based procedure of 3GPP R8+. For example, in thecontention-based procedure of 3GPP R8+ when the WTRU either thecontention-based procedure is successful, or otherwise thecontention-based procedure fails.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A method for uplink timing alignment in a wirelesstransmit/receive unit (WTRU), the method comprising: receiving on aprimary cell (PCell) a physical downlink control channel (PDCCH) order;wherein the PDCCH order includes a carrier indicator field indicating asecondary cell (SCell) to transmit a physical random access channel(PRACH) transmission; in response to the PDCCH order, transmitting thePRACH transmission; in response to the PRACH transmission, monitoringthe PCell for a random access response (RAR); and in response todetecting an RAR associated with the PRACH transmission, adjusting atiming for the SCell in response to a timing advance included in theRAR.
 2. The method of claim 1 wherein in response to detecting the RARassociated with the PRACH transmission, the timing of a plurality ofSCells is adjusted in response to the timing advance and the PCelltiming is not adjusted in response to the timing advance.
 3. The methodof claim 2 wherein the plurality of SCells are in a same timing advancegroup.
 4. The method of claim 1 wherein the PDCCH order includes anindication of a dedicated preamble and a PRACH mask index.
 5. The methodof claim 1 wherein the PDCCH order is received using a downlink controlinformation (DCI) format 1A.
 6. A wireless transmit/receive unit (WTRU)comprising: circuitry configured to receive on a primary cell (PCell) aphysical downlink control channel (PDCCH) order; wherein the PDCCH orderincludes a carrier indicator field indicating a secondary cell (S Cell)to transmit a physical random access channel (PRACH) transmission; thecircuitry, in response to the PDCCH order, configured to transmit thePRACH transmission; the circuitry, in response to the PRACHtransmission, configured to monitor the PCell for a random accessresponse (RAR); and the circuitry, in response to detecting a RARassociated with the PRACH transmission, configured to adjust a timingfor the SCell in response to a timing advance included in the RAR. 7.The WTRU of claim 6 wherein in response to detecting the RAR associatedwith the PRACH transmission, the circuitry is configured to adjust atiming of a plurality of S Cells in response to the timing advance andthe PCell timing is not adjusted in response to the timing advance. 8.The WTRU of claim 7 wherein the plurality of SCells are in a same timingadvance group.
 9. The WTRU of claim 6 wherein the PDCCH order includesan indication of a dedicated preamble and a PRACH mask index.
 10. TheWTRU of claim 6 wherein the PDCCH order is received using a downlinkcontrol information (DCI) format 1A.
 11. An eNodeB comprising: circuitryconfigured to transmit on a primary cell (PCell) a physical downlinkcontrol channel (PDCCH) order to a wireless transmit receive unit(WTRU); wherein the PDCCH order includes a carrier indicator fieldindicating a secondary cell (SCell) to transmit a physical random accesschannel (PRACH) transmission; and the circuitry, in response to a PRACHtransmission received on the secondary cell, configured to transmit onthe PCell a random access response (RAR); and wherein the RAR includes atiming advance to adjust a timing of the WTRU for the SCell.
 12. TheeNodeB of claim 11 wherein the RAR includes a timing advance to adjust atiming of a plurality of SCells and not the PCell.
 13. The eNodeB ofclaim 12 wherein the plurality of SCells are in a same timing advancegroup.
 14. The eNodeB of claim 11 wherein the PDCCH order includes anindication of a dedicated preamble and a PRACH mask index.
 15. TheeNodeB of claim 11 wherein the PDCCH order is transmitted using adownlink control information (DCI) format 1A.